Printing device



April 3, 1962 T. B. TACKETT 3,027,988

PRINTlNG DEVICE Filed Nov. 1'7, 1960 INVENTOR.

THOMAS H. TACKETT ATTORNEY.

United States Patent Office 3,627,988 Patented Apr. 3, 1962 3,927,988 PRINTING DEVICE Thomas B. Tackett, Lexington, Ky., assignor to International Business Machines Corporation, New York, N.Y., a corporation of New York Filed Nov. 17, 1960, Ser. No. 69,955 2 Claims. (Cl. 197-52) This invention relates to printing devices, and more particularly to printing heads having means for releasably attaching them to a drive member.

There is shown in Patent No. 2,895,584 to I. E. Hickerson et al. a printing mechanism including a print head which may be rotated and tilted to present any one of various characters on its surface to a platen. The head is in the shape of a truncated spherical shell and is connected to a drive member extending through its center. It is desirable that the connecting means be releasable manually so the head may be replaced by another bearing characters of a different style.

An object of this invention is to provide a print head having improved means for attaching it to a drive member.

Another object is to provide a print head having a spring element which is movable to a position engaging a drive member for connecting the head thereto, the spring operating in such position to releasably latch itself to the head.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the drawings, which disclose, by way of example, the principle of the invention and the best mode which has been contemplated, of applying that principle.

In the drawings.

FIG. 1 is a plan view, with portions broken away, showing the improved print head and spring element holding it in place on a drive member.

FIG. 2 is an enlarged vertical sectional view taken on the plane of the line 2-2 in FIG. 1.

FIG. 3 is an enlarged fragmentary sectional view taken on a vertical plane including the line 33 of FIG. 1.

FIG. 4 is the like FIG. 3 but shows the spring element moved to a released position.

There is shown in the drawings a print head 1 which is generally like that of the Hickerson et al. patent refer-red to above. The head is in the shape of a truncated spherical shell which is open at its lower end and closed at its upper end except for an opening 2 extending axially through its upper surface and through a cylindrical portion 3 projecting into its interior. Formed on the spherical surface portion of the shell are characters 4 which may be presented selectively to a platen, not shown, by rotating and tilting the head about its center.

Extending upwardly through the vertical axis of the head are driving means including a member 6 which fits within the opening 2 and has an annular flange 7 rwting upon a shoulder 8 on a supporting block 10 pivoted at 11 for tilting motion about a horizontal axis. An annular plate 12 is connected to the top of the block 10 by screws 14 and overlies the flange 7 for holding the member 6 in place during tilting and yet permitting rotation of the member relative to the block.

The lower end of the cylindrical portion 3 rests upon the flange 7, and a pin 16 extends through openings in the member 6 and a notch 17 in the lower end of the cylindrical portion for connecting the head to the member 6 for rotation therewith. As shown by the Hickerson et a1. patent, a forked member engages the pin 16 for rotating the member 6 and the head 1 while permitting a tilting of both with the supporting block.

Attached to the top surface or the head is a cap 19 which may be molded from any suitable plastic material.

The cap is recessed at its lower side to provide between it and the head a space 20 into which the upper end of the drive member 6 projects. Formed integral with the cap are stud portions 22 which extend through openings 23 in the upper surface of the print head. After the cap has been mounted on the head with the stud portions extending through the openings 23, a heated instrument is applied to the lower ends of the stud portions for softening and deforming them in a manner to secure the cap firmly to the head. The other edge of the cap is circular to conform with the top surface of the print head except for a straight edge portion 25 which cuts across the head surface. A clearance 26 is provided between the cap and the head along the straight edge 25 but the cap turns down slightly along this edge to provide a latching portion 27. The edge of the cap throughout its circular portion fits against the top of the head as shown in FIG. 2. The width of the clearance 26 is slightly less than the width of the space 20 so there is provided, as shown in FIG. 1, shoulders 28 and 29 which limit the outward movement of a spring element 30.

The spring element 30 is in the form of a plate which is bifurcated at its inner end to form two arms 32 and 33, their overall width being slightly less than the width of the space 20. A reduced portion 34 of the spring element extends through the clearance 26 and is connected in any suitable manner to a button 35 which may be made of the same material as the cap 19. As shown in FIGS. 1 and 3, the button 35 cooperates with the cap 19 to form a circular cover for the top of the print head when the spring element is moved inwardly to its operative position. With the spring element in this position, a lip 36 on the button engages the latching portion 27 on the cap for holding the spring against accidental release.

At the upper end of the drive member 6 is a head 40 which is formed by cutting an annular groove 41 in the member 6. The head 40 extends into the space 20 when the print head is mounted on the flange 7 of the drive member. The inner edges of the arms 32, 33 on the spring element extend through the groove 41 at opposite sides of the head 40, and the spring arms are transversely bowed so they act on the lower side of the head 40 to hold the print head in place. Spring 38 is also bent upward at a point adjacent the button 35 for holding the latter normally in a raised position. This results in a latching of the button to the cap portion 27 when the spring element is moved to its inner position. The thickness of the button is slightly less than that of the cap 19 so a clearance 42 is provided beneath the button when in its latched position. This permits the button to be depressed manually for releasing it from the cap and permitting withdrawal of the spring element to the position shown in FIG. 4. At this time, shoulders 44, 45 on the spring arms 32, 33 engage the shoulders 28, 29 on the cap for limiting outward movement of the spring. Formed on the button is a raised edge 46 against which the operator may apply force for withdrawing the spring. The cap 19 is also provided with a raised edge like that on the button so as to present at the top of the print head a pattern which is symmetrical throughout its circumference.

When the spring 30 is in the position shown in FIG. 4, the inner ends of the spring arms are clear of the head 40 and permit removal of the print head from its driving means. To connect the print head to the driving means, it is only necessary to slide the spring inwardly until its bowed portions act on the lower side of the head 40 and the button latches itself to the cap 19.

While there have been shown and described the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that it may be modified and embodied in various other forms without O departing from the spirit of the invention. It is intended to be limited only as indicated by the scope of the following claims. What I claim is:

1. A print head having means for releasably attaching it to a drive member on which an enlarged portion is formed at one end comprising, in combination, a truncated spherical shell open at one end and closed at its other end except for an opening extending axially therethrough, a cap attached to the closed end of said shell and forming a space over said opening, said opening adapted to receive said drive member While its enlarged portion is located in said space above said closed end, said cap having a portion of its periphery circular to conform with the closed end of said shell and another portion in the form of a straight edge cutting across the surface of said closed end, said straight portion formed to provide a clearance between said cap and said closed end, a downwardly projecting latching portion on said cap along said straight portion, a spring element slidably extending through said clearance into said space, said spring element being bifurcated at its inner end to form arm portions extending along opposite sides of the center of said opening, a button attached to the outer end of said spring element and having a lip engageable with the latching portion of said cap, said spring element normally holding said button in a position with its lip engaging said latching portion, said spring arms being bowed upwardly to engage the lower side of said enlarged portion at points adjacent said opening when said button is latched to said cap, and said button being operable manually to unlatch it from said cap and to slide said spring element outwardly to a position free of said opening.

2. The mechanism of claim 1 in which inwardly projecting shoulders are provided on said cap at opposite ends of said clearance, and shoulders on said spring element engageable with the shoulders on said cap for limiting the outward movement of said spring element.

References Cited in the file of this patent UNITED STATES PATENTS 409,073 Stover Aug. 13, 1889 1,723,240 Huie Aug. 6, 1929 2,969,864 Holgate Jan. 31, 1961 

